Convert to TypeScript

[bkeepers]

Full disclosure: this was mostly done by Co-pilot in VSCode, with some guidance and changes from me. I will verify test counts and coverage before/after, and go through a careful review.

[Copilot]

Pull request overview

This PR converts the entire codebase from JavaScript to TypeScript, adding type safety throughout the library. The conversion was primarily done using GitHub Copilot with manual review and adjustments.

Key changes:

• Added comprehensive TypeScript type definitions and interfaces across all modules
• Configured TypeScript compilation with tsconfig.json targeting ESNext
• Updated build process to use TypeScript compiler instead of Rollup
• Removed old bundled distribution files in favor of TypeScript compilation output

Reviewed changes

Copilot reviewed 15 out of 22 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tsconfig.json	New TypeScript configuration with strict mode and ESNext targeting
package.json	Updated build scripts to use tsc, added TypeScript dependencies, changed main entry to compiled dist output
src/index.ts	Converted main entry with typed interfaces for TidePrediction API; contains API breaking change in getExtremesPrediction signature
src/node-corrections/index.ts	Added type definitions for node correction functions with AstroData parameter types
src/harmonics/prediction.ts	Added comprehensive interfaces for Timeline, Extreme, TimelinePoint and prediction options
src/harmonics/index.ts	Added typed interfaces for Harmonics factory and options
src/constituents/index.ts	Added Constituents interface defining all constituent types; uses Partial with non-null assertions
src/constituents/constituent.ts	Added Constituent interface with typed astronomy functions
src/constituents/compound-constituent.ts	Added CompoundConstituent and ConstituentMember interfaces
src/astronomy/index.ts	Added AstroData and AstroValue interfaces with typed astronomy calculations
src/astronomy/constants.ts	Converted to TypeScript exports of mathematical constants
src/astronomy/coefficients.ts	Added Coefficients interface and default parameter syntax
rollup.config.js	Removed - no longer needed with TypeScript compilation
dist/*	Removed old bundled distribution files
.gitignore	Added dist, TypeScript build artifacts to ignore list

Comments suppressed due to low confidence (7)

src/harmonics/prediction.ts:143

• The type assertion to empty object (as Prediction) bypasses TypeScript's type checking. This object is later populated with methods, but initializing it this way could lead to runtime errors if the object is accessed before all methods are assigned. Consider defining all methods in the object literal initialization instead.
  src/harmonics/index.ts:63
• Using any[] type for constituents array loses type safety. Since constituents have a known structure with _model and other properties (as defined in HarmonicConstituent interface), this should be typed as HarmonicConstituent[] or a more specific type that includes the _model and _phase properties.
  src/node-corrections/index.ts:4
• The NodeCorrectionFunction type uses any[] for variadic arguments, which bypasses type checking. Consider using a more specific type or a union of allowed parameter types to maintain type safety, or use overloads for functions with different signatures like fModd and uModd that take a number parameter.
  src/harmonics/index.ts:87
• The type assertion to empty object (as Harmonics) bypasses type checking. Consider initializing the object with all required methods in a single object literal to ensure type safety and avoid potential runtime errors if methods are called before assignment.
  src/astronomy/index.ts:216
• Multiple type assertions using (as any) weaken type safety. These assertions are used when dynamically building the result object. Consider using a more type-safe approach, such as Record<string, AstroValue> for intermediate results and then casting to AstroData at the end after all required properties are populated.
  src/constituents/index.ts:164
• Using Partial<Constituents> and then non-null assertions (!) throughout the code indicates a type safety issue. Consider initializing all basic constituents first before creating compound constituents, then export the complete object as Constituents without needing Partial or non-null assertions.
  src/harmonics/prediction.ts:16
• The interface includes a catch-all index signature [key: string]: any that allows any property to be added to HarmonicConstituent. This weakens type safety and could allow typos or incorrect property names to go undetected. Consider removing this or being more specific about what additional properties are allowed.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (13bea43) to head (b7ee983).
⚠️ Report is 11 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##              main      #159    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files           10        10            
  Lines         1038      1324   +286     
  Branches         0        94    +94     
==========================================
+ Hits          1038      1324   +286     

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